Three-phase induction furnace



Sept. 11, 1962 A. TAGLIAFERRI 3,053,921

THREE-PHASE INDUCTION FURNACE Filed Aug. 1o, 1959 Fig/.7

ATTDLNEHS United States Patent O 3,053,921 THREE-PHASE INDUCTION FURNAE Aldo Tagliaferri, Viaie Certosa 59, Milan, Italy Filed Aug. 10, 1959, Ser. No. 832,823 1 Claim. (Cl. 13-28) As is known, in the production of special pig irons or steels, in :addition to suitably high temperatures, a quick and active stirring of the liquid bath in the furnace is required.

For some time attempts have also ybeen made at using cores capable of transmitting by induction an electric power to `a liquid bath, but it has never proved feasible to apply 4directly to a bath a three-phase power, while this would permit using high powers balanced in the three phases, causing a fast dilfusion of the heat to the entire bath and an active stirring of the latter through the electrodynamic movement imparted on the whole liquid mass,

The furnace which forms the object of this invention, the characteristics of which lare illustrated in the following `disclosu-re and in Ithe enclosed drawing, provides a solution for the above problem and offers impor-tant advantages, such as: it lends itself to the melting of any metal or alloy; it permits the reaching o-f any temperature within the range of resistance of the lining; it leaves the furnace entirely free for inspection in case of need.

Lastly, the eicient arrangement of the three inductor coils makes it possible to feed into the furnace a high power, while maintaining a good natural power factor of the furnace, thus achieving an appreciable saving in the application of condensers.

Further advantages of the furnace which forms the object of this invention will be evident from the following detailed description and with reference to the enclosed drawing which represents, as a non-limiting example, one preferred embodiment hereof.

In the tables:

FIGURE 1 is a cross-section longitudinal elevation view of the furnace;

FIGURE 2 represents a plan in cross section of the furnace with the lid removed.

FIGURE 3 is a transverse cross section taken along plane II-II of FIGURE 2.

With reference to the gures, crucible 5 of heavy plate, fitted with lfirebrick linings 6 and iireclay linings 7 according to known methods, rests upon the frame 8 to which are fastened sturdy coaxial pivots 9. On the latter :are articulated the heads of the pistons of two hydraulic rams 10, in turn mounted pivotably on pins 11, fastened to the floor of the furnace pit. Two side brackets 12 carry two coaxial pivots 13 around which frame 8 can be tilted. When the two hydraulic rams are actuated, pivots 9 pass from position 9 to position 9', over an arc of circle indicated in a broken line in FIG- URE 3.

The crucible is covered iby a lid 15 similarly tted with a tire-resistant and insulating lining 16.

The lid has three holes, to each of which corresponds Patented Sept. 11, 1962 ICC a core 18 projecting into its own cylinrical chamber with the corresponding coil 19, above which is provided a space 20 where cooling water is circulated within a suitablejacket.

The three cores are magnetically connected together by a triangular yoke 21. This yoke is dismountable and removable; while the arrangement of the cores and coils is such `that the surrounding liquid bath is in the best condition to receive their magnetic ux `as well as to ensure a satisfactory stirring of the bath and reaching in a short time the requisite temperature; the arrangement of the heating coils with respect to the walls, as shown in particular by FIGURES -l and 3, is such as to ensure a perfectly uniform temperature distribution.

The power Isupply cables, blowers and other auxiliaries of the furnace are realized in accordance with known techniques.

With the type of furnace described above the three heating elements may be arranged in such a way that the respective ducts are spaced lwith respect to each other, by not less than 2 inches and not more than 8 inches, depending on the type of metal or alloy to be melted.

In the type of furnace illustrated in the tigures for purposes of exemplilication, the three cores are closer to the pouring lip in order to facilitate the charging with solid material through the doors 22 `and 22', but the three magnetic elements may be arranged in the center of the crucible when liquid material is to be charged.

Constructional variations may be introduced in the furnace las described above without 'falling outside the scope of the invention when such variations, being inspired by the novel concepts lset forth above, tend to achieve the same or a similar result.

What I claim is:

An electric induction furnace operating on electric power at power mains frequency for producing ferrous and non-ferrous materials, comprising a crucible having .a pouring lip at one side, a three-phase system consisting of three cores and three coils disposed in said crucible and the ilux of which acts directly on the mass to be heated, said coil-s extending from the bottom of said crucible to a point above the normal material level thereof, a yoke mounted on top of and magnetically interconnecting each of the cores, and a jacket disposed above the coil of each magnetic core and in the space left by the core with-in which cooling water circulates; the three magnetic elements and the yoke being eccentrically disposed in said crucible with respect to the central vertical axis thereof and near the pouring lip.

References Cited in the tile of this patent UNITED STATES PATENTS 800,857 Kjellin Oct. 3, 1905 950,911 Gredt May l, 1910 969,261 De Ferranti Sept. 6, 1910 1,011,769 Gehrkens Dec. 12, 1911 1,275,206 Bockman Aug. 13, 1918 2,838,588 Tagliaferri .lune 10, 1958 

